Photographic reflection print material with improved keeping properties

Abstract

A method of making a photographic paper support having improved raw stock keeping characteristics by an internal acid sizing step and an external alkaline sizing step to achieve a water extractable pH of from 6 to 9.5.

What is claimed is: 
     
       1. In the method of making a photographic paper support including the steps of internally sizing the aqueous pulp paper furnish with an acid sizing agent, forming the paper from the furnish, drying the paper and coating the paper on each surface with a polyolefin resin the improvement which comprises externally sizing the paper prior to application of the polyolefin coating with an aqueous alkaline medium to achieve a water extractable pH of the paper of from 6 to 9.5. 
     
     
       2. The method of claim 1 wherein the paper is externally sized so that the water extracted pH is from 6.5 to 8.5. 
     
     
       3. The method of claim 1 wherein the water extracted pH is from 7 to 8. 
     
     
       4. The method of claim 1 wherein the external sizing step is conducted in-line in the steps of making the paper when the paper contains less than 10 percent by weight of water. 
     
     
       5. The method of claim 4 wherein the water content is less than 5 percent by weight. 
     
     
       6. The method of claim 4 wherein the water content is from about 2 to about 4 percent by weight. 
     
     
       7. The method of claim 1 wherein the external sizing step is conducted off-line after the paper is formed and before it is coated. 
     
     
       8. The method of claim 1 wherein the pH of the aqueous pulp furnish is from 4 to 5.5. 
     
     
       9. The method of claim 8 wherein the pH of the aqueous pulp furnish is from 4 to 4.8. 
     
     
       10. The method of claim 8 wherein the pH of the aqueous pulp furnish is from 4.2 to 4.5. 
     
     
       11. The method of claim 1 wherein the aqueous alkaline medium is an alkali metal base. 
     
     
       12. The method of claim 11 wherein the alkali metal base is sodium or potassium. 
     
     
       13. The method of claim 11 wherein the alkali metal base is sodium bicarbonate, potassium bicarbonate, sodium hydroxide, or potassium hydroxide.